1. Technical Field
The present invention relates to a liquid discharging apparatus, a head unit, a capacitive load driving circuit, and an integrated circuit device.
2. Related Art
In a liquid discharging apparatus, such as an ink jet printer, which discharges ink and prints an image or a document, an apparatus which uses a piezoelectric element (for example, a piezo element) has been known. The piezoelectric elements are provided corresponding to each of a plurality of nozzles in a head unit, and each of the piezoelectric elements is driven in accordance with driving signals. Accordingly, a predetermined amount of ink (liquid) is discharged from the nozzle at a predetermined timing, and a dot is formed. Since the piezoelectric element is a capacitive load, such as a capacitor, in terms of electricity, it is necessary to supply sufficient amount of current in order to operate the piezoelectric elements of each nozzle.
For this reason, in the above-described liquid discharging apparatus, the piezoelectric elements are driven as a driving signal which is amplified by an amplifying circuit is supplied to a head unit (ink jet head). An example of the amplifying circuit includes a type which performs current amplification with respect to a source signal before the amplification by using a class-AB amplifier, but since energy efficiency is not excellent, in recent years, a type in which a class-D amplifier is used has been suggested (refer to JP-A-2010-114711).
There is a case where a charge pump circuit which is a boosting circuit is included in an ink jet class-D amplifier IC. One or more boosting capacitors are necessary in the charge pump circuit. In many cases, the boosting capacitor is connected to the outside of the IC due to the influence of the size or the like. In addition, since two terminals of the boosting capacitor are connected to an adjacent terminal of the IC, in a case where a plurality of capacitors are necessary, when the capacitors are disposed being adjacent to each other simply by using a plurality of terminals which protrude from one side of a package, the disposition between the capacitors is interfered with and the wiring length becomes long. Accordingly, there is a possibility that a problem, such as an increase in a circuit area or deterioration of discharge accuracy due to the influence of noise on the charge pump, is generated.